Key result
Angulation of the LVAD inflow cannula by 15° toward the septum increased apical stasis, doubled the size of the counterclockwise vortex, and significantly decreased average and systolic velocities.
Why the study?
Does inflow cannula angulation alter the intraventricular flow field and increase stasis in an in vitro LVAD model?
Does inflow cannula angulation alter the intraventricular flow field and increase stasis in an in vitro LVAD model?
In vitro flow visualization demonstrates that a 15-degree malposition of an LVAD inflow cannula significantly worsens intraventricular flow dynamics and increases stasis, highlighting the importance of precise surgical positioning.
Precise LVAD inflow positioning may limit apical stasis; leaves open effects on clinical thrombosis.
Previous studies have identified left ventricular assist device (LVAD) inflow cannula (IC) malposition as a significant risk for pump thrombosis. Thrombus development is a consequence of altered flow dynamics, which can produce areas of flow stasis or high shear that promote coagulation. The goal of this study was to measure the effect of IC orientation on the left ventricle (LV) flow field using a mock circulatory loop, and identify flow-based indices that are sensitive measures of cannula malposition. Experimental studies were performed with a customized silicone model of the dilated LV and the EVAHEART Centrifugal LVAS (Evaheart, Inc.; Houston TX). The velocity field of the LV midplane was measured for a transparent IC oriented parallel to and rotated 15° toward the septum under matched hemodynamic conditions. Vortex structures were analyzed and localized stasis calculated within the IC and combined with a map of normalized pulsatile velocity. The velocity fields revealed increased apical stasis and lower pulsatility with a small angulation of the IC. A significant change in vortex dynamics with the angled IC was observed, doubling the size of the counterclockwise (CCW) vortex while reducing the kinetic energy provided by LVAD support. A significant decrease in average and systolic velocities within the IC was found with cannula angulation, suggesting an increased resistance that affects primarily systolic flow and is worsened with increased LVAD support. These common echocardiographic indices offer the opportunity for immediate clinical application during ramp study assessment. Optimized IC positioning may be determined preoperatively using imaging techniques to develop patient-specific surgical recommendations.
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May‐Newman et al. (2018) studied Left ventricular assist device (LVAD) support. Inflow cannula angulation (15° toward the septum) vs. Inflow cannula oriented parallel was evaluated on Velocity field, vortex structures, and localized stasis within the inflow cannula and left ventricle. Angulation of the LVAD inflow cannula by 15° toward the septum increased apical stasis, doubled the size of the counterclockwise vortex, and significantly decreased average and systolic velocities.
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